Power generation from inverter-based renewable energy sources (RESs)

such as solar photovoltaics (PVs)

is increasing rapidly in power systems while leading to operational challenges such as frequency regulation. Battery energy storage systems (BESS) have attracted much attention in providing frequency control ancillary services (FCAS)

as they provide flexibility to store and release energy when required. With a larger inverter size and energy capacity

BESS can provide more frequency support to the grid but will incur large capital costs. Thus

it is important to minimise the size of the battery while ensuring system security requirements are fulfilled. In this paper

a large-scale BESS sizing framework is developed to obtain the optimal battery inverter size and energy capacity. The proposed framework determines the battery size based on two aspects: (i) contingency frequency control ancillary services (C-FCAS) to provide primary frequency support after a generator outage event and (ii) regulating frequency control ancillary service (R-FCAS) to match the power imbalance caused by the normal variation of load demand and RES generation. This paper also investigates the highest RES penetration level and the largest number of synchronous generators (SGs) that can be simultaneously reduced as the share of RESs increases. The effectiveness of the developed large-scale BESS sizing framework is tested on the Alice Springs power grid in Northern Territory

Australia. According to the study

the FCAS battery designed based on the proposed framework can fulfil the frequency support requirements under high solar-PV penetration in the Alice Springs power grid while significantly reducing the dependency on synchronous generators.